[ { "@id": "https://w3id.org/sciencelive/np/RAGe9U1qrzbrHI6bZjkM7d3vuwbAkv5j1K0S5cEC8HYkk/assertion", "@graph": [ { "@id": "https://w3id.org/sciencelive/np/RAGe9U1qrzbrHI6bZjkM7d3vuwbAkv5j1K0S5cEC8HYkk/turbidity-strong-limb-open-source-westerschelde", "http://schema.org/endDate": [ { "@value": "2026-07-25", "@type": "http://www.w3.org/2001/XMLSchema#date" } ], "@type": [ "https://w3id.org/sciencelive/o/terms/FORRT-Replication-Outcome" ], "http://www.w3.org/2000/01/rdf-schema#label": [ { "@value": "Open-source Sentinel-2 turbidity retrieval in the Westerschelde confirms the Sado strong-turbidity finding" } ], "https://w3id.org/sciencelive/o/terms/hasConclusionDescription": [ { "@value": "This replication confirms the original claim. Sent et al. (2021) found that\nSentinel-2 MSI retrieves water-quality parameters with parameter-dependent\naccuracy — strong for turbidity, weak for chlorophyll-a — and selected a\nC2RCC + Nechad (cN783) chain that retrieved turbidity in strong agreement with in\nsitu (R² = 0.84). Testing that turbidity limb in an independent, more turbid\nestuary (the Westerschelde, 2016–2026) with a fully open-source\natmospheric-correction chain (Acolite + Nechad et al. 2010, the aN783 chain), we\nobtained strong agreement with in situ turbidity: R² = 0.92 with a near-unity\nslope (0.86), meeting and slightly exceeding the paper's proprietary result. This\nis the strong side of the parameter asymmetry the paper describes, and it\nreplicates even open-source: an operationally reproducible chain that uses no\nproprietary processor recovers estuarine turbidity at, and slightly beyond, the\naccuracy of the paper's selected cN783 chain, in a different optical regime." } ], "https://w3id.org/sciencelive/o/terms/hasConfidenceLevel": [ { "@id": "https://w3id.org/sciencelive/o/terms/HighConfidence" } ], "https://w3id.org/sciencelive/o/terms/hasEvidenceDescription": [ { "@value": "From results/turbidity_satellite_acolite.parquet, agreement computed in linear\nspace (scripts/matchup_stats.py), matching the paper's linear treatment of\nturbidity (turbidity is reported in FNU on both sides — no unit conversion):\n\n N = 11 match-ups\n R² = 0.92 (ours, aN783) vs R² = 0.84 (original, selected cN783)\n slope = 0.86 (near unity)\n RMSE = 10.13 FNU\n BIAS = +6.91 FNU (slight overestimate)\n\nThe open-source Acolite + Nechad (aN783) chain therefore meets and slightly\nexceeds the original study's selected C2RCC + Nechad (cN783) R² of 0.84, with a\nnear-unity regression slope, in a different and more turbid estuary. The small\npositive bias (+6.91 FNU) indicates a mild systematic overestimate but does not\ndegrade the correlation. Turbidity is the strong side of the parameter asymmetry\nseen across the three retrieved parameters. Match-up figure: figures/asymmetry.png." } ], "https://w3id.org/sciencelive/o/terms/hasLimitationsDescription": [ { "@value": "Four factors bound this conclusion.\n\n1. Sample size. N = 11 turbidity match-ups is small — fewer valid pairs than the\n Chl-a limb (N = 33), and comparable to the original (N = 19–21). The R² = 0.92\n therefore carries a wide confidence interval. The direction of the result\n (strong agreement, meeting/exceeding the original) is robust; its precise\n magnitude is not.\n\n2. Processor rating. The paper reports Acolite as its worst-performing\n atmospheric-correction processor, yet here the open-source Acolite + Nechad\n chain matches and slightly exceeds the paper's selected C2RCC + Nechad result.\n That is a notable finding, but a single-site one — it should not be read as a\n general claim that Acolite outperforms C2RCC for turbidity everywhere.\n\n3. Site and period change. This is a Replication, not a Reproduction: the Sado in\n situ data are not public (paper Data Availability Statement), so we validated in\n the Westerschelde (2016–2026), a different and more turbid mesotidal estuary.\n A different optical regime tests generalisability, not the correctness of the\n original analysis. Agreement was computed in linear space, matching the paper's\n treatment of turbidity.\n\n4. Systematic bias. The retrieval carries a slight positive bias (+6.91 FNU), a\n mild overestimate that does not degrade the correlation but should be noted for\n any quantitative use.\n\nA grid-sensitivity check on a HEALPix / DGGS (GRID4EARTH) representation of the\ncorrected fields is deliberately out of scope here and deferred to a separate\nfollow-up chain that will extend this one, so the primary validation stays on the\nnative Sentinel-2 grid." } ], "https://w3id.org/sciencelive/o/terms/hasOutcomeRepository": [ { "@id": "https://doi.org/10.5281/zenodo.21561994" } ], "https://w3id.org/sciencelive/o/terms/hasValidationStatus": [ { "@id": "https://w3id.org/sciencelive/o/terms/Validated" } ], "https://w3id.org/sciencelive/o/terms/isOutcomeOf": [ { "@id": "https://w3id.org/sciencelive/np/RAnwDtIlAWIqvXpldc4jr_BhZF10mbn1nSMjcBFieDfy4" } ] } ] }, { "@id": "https://w3id.org/sciencelive/np/RAGe9U1qrzbrHI6bZjkM7d3vuwbAkv5j1K0S5cEC8HYkk/pubinfo", "@graph": [ { "@id": "https://orcid.org/0000-0002-1784-2920", 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